Root/crypto/lrw.c

1/* LRW: as defined by Cyril Guyot in
2 * http://grouper.ieee.org/groups/1619/email/pdf00017.pdf
3 *
4 * Copyright (c) 2006 Rik Snel <rsnel@cube.dyndns.org>
5 *
6 * Based on ecb.c
7 * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
8 *
9 * This program is free software; you can redistribute it and/or modify it
10 * under the terms of the GNU General Public License as published by the Free
11 * Software Foundation; either version 2 of the License, or (at your option)
12 * any later version.
13 */
14/* This implementation is checked against the test vectors in the above
15 * document and by a test vector provided by Ken Buchanan at
16 * http://www.mail-archive.com/stds-p1619@listserv.ieee.org/msg00173.html
17 *
18 * The test vectors are included in the testing module tcrypt.[ch] */
19
20#include <crypto/algapi.h>
21#include <linux/err.h>
22#include <linux/init.h>
23#include <linux/kernel.h>
24#include <linux/module.h>
25#include <linux/scatterlist.h>
26#include <linux/slab.h>
27
28#include <crypto/b128ops.h>
29#include <crypto/gf128mul.h>
30#include <crypto/lrw.h>
31
32struct priv {
33    struct crypto_cipher *child;
34    struct lrw_table_ctx table;
35};
36
37static inline void setbit128_bbe(void *b, int bit)
38{
39    __set_bit(bit ^ (0x80 -
40#ifdef __BIG_ENDIAN
41             BITS_PER_LONG
42#else
43             BITS_PER_BYTE
44#endif
45            ), b);
46}
47
48int lrw_init_table(struct lrw_table_ctx *ctx, const u8 *tweak)
49{
50    be128 tmp = { 0 };
51    int i;
52
53    if (ctx->table)
54        gf128mul_free_64k(ctx->table);
55
56    /* initialize multiplication table for Key2 */
57    ctx->table = gf128mul_init_64k_bbe((be128 *)tweak);
58    if (!ctx->table)
59        return -ENOMEM;
60
61    /* initialize optimization table */
62    for (i = 0; i < 128; i++) {
63        setbit128_bbe(&tmp, i);
64        ctx->mulinc[i] = tmp;
65        gf128mul_64k_bbe(&ctx->mulinc[i], ctx->table);
66    }
67
68    return 0;
69}
70EXPORT_SYMBOL_GPL(lrw_init_table);
71
72void lrw_free_table(struct lrw_table_ctx *ctx)
73{
74    if (ctx->table)
75        gf128mul_free_64k(ctx->table);
76}
77EXPORT_SYMBOL_GPL(lrw_free_table);
78
79static int setkey(struct crypto_tfm *parent, const u8 *key,
80          unsigned int keylen)
81{
82    struct priv *ctx = crypto_tfm_ctx(parent);
83    struct crypto_cipher *child = ctx->child;
84    int err, bsize = LRW_BLOCK_SIZE;
85    const u8 *tweak = key + keylen - bsize;
86
87    crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
88    crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
89                       CRYPTO_TFM_REQ_MASK);
90    err = crypto_cipher_setkey(child, key, keylen - bsize);
91    if (err)
92        return err;
93    crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
94                     CRYPTO_TFM_RES_MASK);
95
96    return lrw_init_table(&ctx->table, tweak);
97}
98
99struct sinfo {
100    be128 t;
101    struct crypto_tfm *tfm;
102    void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
103};
104
105static inline void inc(be128 *iv)
106{
107    be64_add_cpu(&iv->b, 1);
108    if (!iv->b)
109        be64_add_cpu(&iv->a, 1);
110}
111
112static inline void lrw_round(struct sinfo *s, void *dst, const void *src)
113{
114    be128_xor(dst, &s->t, src); /* PP <- T xor P */
115    s->fn(s->tfm, dst, dst); /* CC <- E(Key2,PP) */
116    be128_xor(dst, dst, &s->t); /* C <- T xor CC */
117}
118
119/* this returns the number of consequative 1 bits starting
120 * from the right, get_index128(00 00 00 00 00 00 ... 00 00 10 FB) = 2 */
121static inline int get_index128(be128 *block)
122{
123    int x;
124    __be32 *p = (__be32 *) block;
125
126    for (p += 3, x = 0; x < 128; p--, x += 32) {
127        u32 val = be32_to_cpup(p);
128
129        if (!~val)
130            continue;
131
132        return x + ffz(val);
133    }
134
135    return x;
136}
137
138static int crypt(struct blkcipher_desc *d,
139         struct blkcipher_walk *w, struct priv *ctx,
140         void (*fn)(struct crypto_tfm *, u8 *, const u8 *))
141{
142    int err;
143    unsigned int avail;
144    const int bs = LRW_BLOCK_SIZE;
145    struct sinfo s = {
146        .tfm = crypto_cipher_tfm(ctx->child),
147        .fn = fn
148    };
149    be128 *iv;
150    u8 *wsrc;
151    u8 *wdst;
152
153    err = blkcipher_walk_virt(d, w);
154    if (!(avail = w->nbytes))
155        return err;
156
157    wsrc = w->src.virt.addr;
158    wdst = w->dst.virt.addr;
159
160    /* calculate first value of T */
161    iv = (be128 *)w->iv;
162    s.t = *iv;
163
164    /* T <- I*Key2 */
165    gf128mul_64k_bbe(&s.t, ctx->table.table);
166
167    goto first;
168
169    for (;;) {
170        do {
171            /* T <- I*Key2, using the optimization
172             * discussed in the specification */
173            be128_xor(&s.t, &s.t,
174                  &ctx->table.mulinc[get_index128(iv)]);
175            inc(iv);
176
177first:
178            lrw_round(&s, wdst, wsrc);
179
180            wsrc += bs;
181            wdst += bs;
182        } while ((avail -= bs) >= bs);
183
184        err = blkcipher_walk_done(d, w, avail);
185        if (!(avail = w->nbytes))
186            break;
187
188        wsrc = w->src.virt.addr;
189        wdst = w->dst.virt.addr;
190    }
191
192    return err;
193}
194
195static int encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
196           struct scatterlist *src, unsigned int nbytes)
197{
198    struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
199    struct blkcipher_walk w;
200
201    blkcipher_walk_init(&w, dst, src, nbytes);
202    return crypt(desc, &w, ctx,
203             crypto_cipher_alg(ctx->child)->cia_encrypt);
204}
205
206static int decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
207           struct scatterlist *src, unsigned int nbytes)
208{
209    struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
210    struct blkcipher_walk w;
211
212    blkcipher_walk_init(&w, dst, src, nbytes);
213    return crypt(desc, &w, ctx,
214             crypto_cipher_alg(ctx->child)->cia_decrypt);
215}
216
217int lrw_crypt(struct blkcipher_desc *desc, struct scatterlist *sdst,
218          struct scatterlist *ssrc, unsigned int nbytes,
219          struct lrw_crypt_req *req)
220{
221    const unsigned int bsize = LRW_BLOCK_SIZE;
222    const unsigned int max_blks = req->tbuflen / bsize;
223    struct lrw_table_ctx *ctx = req->table_ctx;
224    struct blkcipher_walk walk;
225    unsigned int nblocks;
226    be128 *iv, *src, *dst, *t;
227    be128 *t_buf = req->tbuf;
228    int err, i;
229
230    BUG_ON(max_blks < 1);
231
232    blkcipher_walk_init(&walk, sdst, ssrc, nbytes);
233
234    err = blkcipher_walk_virt(desc, &walk);
235    nbytes = walk.nbytes;
236    if (!nbytes)
237        return err;
238
239    nblocks = min(walk.nbytes / bsize, max_blks);
240    src = (be128 *)walk.src.virt.addr;
241    dst = (be128 *)walk.dst.virt.addr;
242
243    /* calculate first value of T */
244    iv = (be128 *)walk.iv;
245    t_buf[0] = *iv;
246
247    /* T <- I*Key2 */
248    gf128mul_64k_bbe(&t_buf[0], ctx->table);
249
250    i = 0;
251    goto first;
252
253    for (;;) {
254        do {
255            for (i = 0; i < nblocks; i++) {
256                /* T <- I*Key2, using the optimization
257                 * discussed in the specification */
258                be128_xor(&t_buf[i], t,
259                        &ctx->mulinc[get_index128(iv)]);
260                inc(iv);
261first:
262                t = &t_buf[i];
263
264                /* PP <- T xor P */
265                be128_xor(dst + i, t, src + i);
266            }
267
268            /* CC <- E(Key2,PP) */
269            req->crypt_fn(req->crypt_ctx, (u8 *)dst,
270                      nblocks * bsize);
271
272            /* C <- T xor CC */
273            for (i = 0; i < nblocks; i++)
274                be128_xor(dst + i, dst + i, &t_buf[i]);
275
276            src += nblocks;
277            dst += nblocks;
278            nbytes -= nblocks * bsize;
279            nblocks = min(nbytes / bsize, max_blks);
280        } while (nblocks > 0);
281
282        err = blkcipher_walk_done(desc, &walk, nbytes);
283        nbytes = walk.nbytes;
284        if (!nbytes)
285            break;
286
287        nblocks = min(nbytes / bsize, max_blks);
288        src = (be128 *)walk.src.virt.addr;
289        dst = (be128 *)walk.dst.virt.addr;
290    }
291
292    return err;
293}
294EXPORT_SYMBOL_GPL(lrw_crypt);
295
296static int init_tfm(struct crypto_tfm *tfm)
297{
298    struct crypto_cipher *cipher;
299    struct crypto_instance *inst = (void *)tfm->__crt_alg;
300    struct crypto_spawn *spawn = crypto_instance_ctx(inst);
301    struct priv *ctx = crypto_tfm_ctx(tfm);
302    u32 *flags = &tfm->crt_flags;
303
304    cipher = crypto_spawn_cipher(spawn);
305    if (IS_ERR(cipher))
306        return PTR_ERR(cipher);
307
308    if (crypto_cipher_blocksize(cipher) != LRW_BLOCK_SIZE) {
309        *flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
310        crypto_free_cipher(cipher);
311        return -EINVAL;
312    }
313
314    ctx->child = cipher;
315    return 0;
316}
317
318static void exit_tfm(struct crypto_tfm *tfm)
319{
320    struct priv *ctx = crypto_tfm_ctx(tfm);
321
322    lrw_free_table(&ctx->table);
323    crypto_free_cipher(ctx->child);
324}
325
326static struct crypto_instance *alloc(struct rtattr **tb)
327{
328    struct crypto_instance *inst;
329    struct crypto_alg *alg;
330    int err;
331
332    err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
333    if (err)
334        return ERR_PTR(err);
335
336    alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
337                  CRYPTO_ALG_TYPE_MASK);
338    if (IS_ERR(alg))
339        return ERR_CAST(alg);
340
341    inst = crypto_alloc_instance("lrw", alg);
342    if (IS_ERR(inst))
343        goto out_put_alg;
344
345    inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
346    inst->alg.cra_priority = alg->cra_priority;
347    inst->alg.cra_blocksize = alg->cra_blocksize;
348
349    if (alg->cra_alignmask < 7) inst->alg.cra_alignmask = 7;
350    else inst->alg.cra_alignmask = alg->cra_alignmask;
351    inst->alg.cra_type = &crypto_blkcipher_type;
352
353    if (!(alg->cra_blocksize % 4))
354        inst->alg.cra_alignmask |= 3;
355    inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
356    inst->alg.cra_blkcipher.min_keysize =
357        alg->cra_cipher.cia_min_keysize + alg->cra_blocksize;
358    inst->alg.cra_blkcipher.max_keysize =
359        alg->cra_cipher.cia_max_keysize + alg->cra_blocksize;
360
361    inst->alg.cra_ctxsize = sizeof(struct priv);
362
363    inst->alg.cra_init = init_tfm;
364    inst->alg.cra_exit = exit_tfm;
365
366    inst->alg.cra_blkcipher.setkey = setkey;
367    inst->alg.cra_blkcipher.encrypt = encrypt;
368    inst->alg.cra_blkcipher.decrypt = decrypt;
369
370out_put_alg:
371    crypto_mod_put(alg);
372    return inst;
373}
374
375static void free(struct crypto_instance *inst)
376{
377    crypto_drop_spawn(crypto_instance_ctx(inst));
378    kfree(inst);
379}
380
381static struct crypto_template crypto_tmpl = {
382    .name = "lrw",
383    .alloc = alloc,
384    .free = free,
385    .module = THIS_MODULE,
386};
387
388static int __init crypto_module_init(void)
389{
390    return crypto_register_template(&crypto_tmpl);
391}
392
393static void __exit crypto_module_exit(void)
394{
395    crypto_unregister_template(&crypto_tmpl);
396}
397
398module_init(crypto_module_init);
399module_exit(crypto_module_exit);
400
401MODULE_LICENSE("GPL");
402MODULE_DESCRIPTION("LRW block cipher mode");
403

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